Is the space effort dying or evolving?

Pessimists are bemoaning the end of U.S. human spaceflight, but optimists see the next few years as a transition to a new paradigm that will energize commercial ventures and get astronauts beyond Earth orbit for the first time since the Nixon administration. Which way do you see it?

There seems to be plenty of gloom to go around as the space shuttle program nears its end. Hayden Planetarium director Neil deGrasse Tyson, a former member of the NASA Advisory Council and other commissions sizing up the space effort, had this to say via Twitter: "Apollo in 1969. Shuttle in 1981. Nothing in 2011. Our space program would look awesome to anyone living backwards through time."

One of the astronauts on the first space shuttle flight in 1981, Bob Crippen, told me that he was disappointed that the shuttle program's end would leave NASA "without the capability to put our astronauts in orbit ourselves." And he questioned whether NASA had the right vision for future exploration. "I personally favored going to the moon," he said.

The frustration flared up today during a House committee hearing with NASA Administrator Charles Bolden as the sole witness, or sole target. "We have waited for answers that have not come," Science, Space and Technology Committee Chairman Ralph Hall, R-Texas, told Bolden. "We have run out of patience. ... I would like to point out today that the committee reserves the right to open an investigation into these continued delays and join the investigation initiated by the Senate."

Bolden, a retired Marine general, took the hostile fire. "You have the right guy here to criticize," he said. "I am the leader of America's space program."

He laid out the main points of the post-shuttle plan:

Rely on the Russians and other partners for resupply of the International Space Station, at least until U.S. companies can finish work on the space vehicles they're developing with NASA's backing. The first commercial cargo craft could be flying to the station by the end of this year, and U.S.-made "space taxis" could be taking on astronauts by 2015.

Continue work on the Orion crew vehicle, which should be capable of carrying four astronauts on more ambitious trips beyond Earth orbit. Orion had been canceled as part of the Constellation back-to-the-moon program, after $5 billion had been spent on the program, but it was essentially resurrected as NASA's "multipurpose crew vehicle," or MPCV.

Build a new Space Launch System, or SLS, which will be based on shuttle-era and Apollo-era rocket technology. The design for the SLS has not yet been announced, which is why members of Congress are so frustrated. Bolden said it could take until the end of summer or even longer to get the SLS plan through its financial review. Congress passed a law calling for the MPCV spaceship and the SLS rocket to be ready by 2016, but Bolden said the 2017-2020 time frame was more realistic.

NASA is aiming to send astronauts to a near-Earth asteroid by 2025, and to Mars and its moons by the mid-2030s. Other stopovers, ranging from the moon to gravitational balance points in outer space, may be added along the way.

"We are not abandoning human spaceflight," Bolden said. "American leadership in space will continue for at least the next half century because we have laid the foundation for success."

So there is an evolving plan for the future ... just as there was an evolving plan for the space shuttle system in the early to mid-1970s when the Apollo program came to an end. Under the best-case scenario, that plan will lead to actual flights within four to six years, which is less time than it took between the last Saturn 5 and the first shuttle launch. But there are lots of questions surrounding the post-shuttle plan:

How much money will NASA get? A draft report from the House Appropriations Committee calls for trimming the space agency's budget by roughly 10 percent. (For details, check Space Policy Online, Parabolic Arc and Space News.) NASA officials as well as commercial spaceship developers say that budget reductions will slow down the transition to post-shuttle spaceflight even more.

Will the commercial sector succeed? Right now, NASA is committed to paying the Russians $56 million for each seat on a station-bound Soyuz craft, and the price is due to go up in 2014. Commercial providers such as SpaceX, Sierra Nevada and the Boeing Co. say that they can beat that price, but that they need NASA's money to help cover development costs. Shuttle program veterans say the commercial providers still have to prove that their craft will be safe and reliable.

Will the commercial space taxis for low Earth orbit and the Orion MPCV/SLS system for going beyond Earth orbit complement each other the way NASA hopes? Larry Price, Lockheed Martin Space Systems' deputy manager for the Orion program, told me that the two-track system served as an insurance policy for the post-shuttle space effort. "There's a little bit of competitive pressure," he acknowledged. "If the commercial guys run into any problem or delay for any reason, then we could back them up. And similarly, if we don't meet our milestones, the commercial guys could evolve into our niche."

After 30 years of grand successes, tragic failures and unfulfilled promises, the era of the space shuttle is ending. We may not yet know exactly what kind of American spaceship will be the next to fly. And because of that, thousands of people will be laid off by NASA and its contractors in the weeks ahead. But we're not witnessing the death of the American space program. At least that's the way Elon Musk, the millionaire founder of SpaceX, sees it.

"As far as I'm concerned, it's not the death of anything," he told me. "What we're really facing is quite the opposite. I think we're at the dawn of a new era of spaceflight, one which is going to advance much faster than it ever has in the past."

Now why would he say that? Over the next few days, we'll be presenting a series of Q&A interviews with Musk and other folks involved in shaping the post-shuttle era. What they've told me runs counter to the gloom-and-doom talk, but you might well have a different opinion. Feel free to weigh in with your comments.